Lots of service are personal services (the thing you are servicing is the customer), and categories of personal service expand and contract with, essentially, fashion. Service can literally be created out of thin air.

Personal trainers, nail artists, psychotherapists, tour guides, social media consultants, maids, window cleaners, YouTubers, Mariachi bands, pet groomers, translators, golf instructors...

This is actually directed at the sibling comment from Houshalter:

I'm pretty sure that people who aren't members of the "rich upper classes" do make use of most of those services. To take just one as an example, nail salons are actually more common in the poorer parts of town in most cities I've been in.

And who is going to pay for those services? All those services are for the rich upper classes that can afford them. Your servant can't afford her own servant.

They reach saturation in a local area quickly and tend to burn out quickly. They also tend these days to not even be year-round work.

Fireworks booths, Halloween shops, frozen yogurt franchises, "escape game" franchises, "curves" gyms targeted towards women, edible fruit arranged like flowers...a lot of service jobs have very short shelf lives, and can really only have one or two in a town.